Apparatus and method for treating glaucoma

ABSTRACT

Surgical methods and related medical devices for treating glaucoma are shown. The method includes trabecular bypass surgery, which involves bypassing diseased trabecular meshwork with the use of a seton implant. The seton implant is used to prevent a healing process known as filling in, which has a tendency to close surgically created openings in the trabecular meshwork. The surgical method and novel implant are addressed to the trabecular meshwork, which is a major site of resistance to outflow in glaucoma. In addition to bypassing the diseased trabecular meshwork at the level of the trabecular meshwork, existing outflow pathways are also used or restored. The seton implant is positioned through the trabecular meshwork so that an inlet end of the seton implant is exposed to the anterior chamber of the eye and an outlet end is positioned into fluid collection channels at about an exterior surface of the trabecular meshwork or up to the level of aqueous veins.

CLAIM OF PRIORITY

This application is a continuation application of U.S. patentapplication Ser. No. 09/549,350, filed Apr. 14, 2000, now U.S. Pat. No.6,638,239, which is incorporated in its entirety by reference herein.

FIELD OF THE INVENTION

The present invention generally relates to improved medical devices andmethods for the reduction of elevated pressure in organs of the humanbody. More particularly, the present invention relates to the treatmentof glaucoma by trabecular bypass surgery, which is a means for using animplant or seton, such as a micro stent, shunt or the like, to bypassdiseased trabecular meshwork at the level of trabecular meshwork anduse/restore existing outflow pathways.

BACKGROUND OF THE INVENTION

About two percent of people in the United States have glaucoma. Glaucomais a group of eye diseases that causes pathological changes in the opticdisk and corresponding visual field loss resulting in blindness ifuntreated. Intraocular pressure elevation is the major etiologic factorin all glaucomas.

In glaucomas associated with an elevation in eye pressure the source ofresistance to outflow is in the trabecular meshwork. The tissue of thetrabecular meshwork allows the “aqueous” to enter Schlemm's canal, whichthen empties into aqueous collector channels in the posterior wall ofSchlemm's canal and then into aqueous veins. The aqueous or aqueoushumor is a transparent liquid that fills the region between the corneaat the front of the eye and the lens. The aqueous humor is constantlysecreted by the ciliary body around the lens, so there is a continuousflow of the aqueous humor from the ciliary body to the eye's frontchamber. The eye's pressure is determined by a balance between theproduction of aqueous and its exit through the trabecular meshwork(major route) or via uveal scleral outflow (minor route). The trabecularmeshwork is located between the outer rim of the iris and the internalperiphery of the cornea. The portion of the trabecular meshwork adjacentto Schlemm's canal causes most of the resistance to aqueous outflow(juxtacanilicular meshwork).

Glaucoma is grossly classified into two categories: closed-angleglaucoma and open-angle glaucoma. The closed-angle glaucoma is caused byclosure of the anterior angle by contact between the iris and the innersurface of the trabecular meshwork. Closure of this anatomical angleprevents normal drainage of aqueous humor from the anterior chamber ofthe eye. Open-angle glaucoma is any glaucoma in which the angle of theanterior chamber remains open, but the exit of aqueous through thetrabecular meshwork is diminished. The exact cause for diminishedfiltration is unknown for most cases of open-angle glaucoma. However,there are secondary open-angle glaucomas which may include edema orswelling of the trabecular spaces (from steroid use), abnormal pigmentdispersion, or diseases such as hyperthyroidism that produce vascularcongestion.

All current therapies for glaucoma are directed at decreasingintraocular pressure. This is initially by medical therapy with drops orpills that reduce the production of aqueous humor or increase theoutflow of aqueous. However, these various drug therapies for glaucomaare sometimes associated with significant side effects, such asheadache, blurred vision, allergic reactions, death from cardiopulmonarycomplications and potential interactions with other drugs. When the drugtherapy fails, surgical therapy is used. Surgical therapy for open-angleglaucoma consists of laser (trabeculoplasty), trabeculectomy and aqueousshunting implants after failure of trabeculectomy or if trabeculectomyis unlikely to succeed. Trabeculectomy is a major surgery which is mostwidely used and is augmented with topically applied anticancer drugssuch as 5-flurouracil or mitomycin-c to decrease scarring and increasesurgical success.

Approximately 100,000 trabeculectomies are performed on Medicare agepatients per year in the United States. This number would increase ifthe morbidity associated with trabeculectomy could be decreased. Thecurrent morbidity associated with trabeculectomy consists of failure(10-15%), infection (a life long risk about 2-5%), choroidal hemorrhage(1%, a severe internal hemorrhage from pressure too low resulting invisual loss), cataract formation, and hypotony maculopathy (potentiallyreversible visual loss from pressure too low).

If it were possible to bypass the local resistance to outflow of aqueousat the point of the resistance and use existing outflow mechanisms,surgical morbidity would greatly decrease. The reason for this is thatthe episcleral aqueous veins have a backpressure that would prevent theeye pressure from going too low. This would virtually eliminate the riskof hypotony maculopathy and choroidal hemorrhage. Furthermore, visualrecovery would be very rapid and risk of infection would be very small(a reduction from 2-5% to 0.05%). Because of these reasons surgeons havetried for decades to develop a workable surgery for the trabecularmeshwork.

The previous techniques, which have been tried, aregoniotomy/trabeculotomy, and other mechanical disruption of thetrabecular meshwork, such as trabeculopuncture, goniophotoablation,laser trabecular ablation and goniocurretage. They are briefly describedbelow.

Goniotomy/Trabeculotomy: Goniotomy and trabeculotomy are simple anddirected techniques of microsurgical dissection with mechanicaldisruption of the trabecular meshwork. These initially had earlyfavorable responses in the treatment of open-angle glaucoma. However,long-term review of surgical results showed only limited success inadults. In retrospect, these procedures probably failed secondary torepair mechanisms and a process of “filling in”. The filling in is theresult of a healing process which has the detrimental effect ofcollapsing and closing in of the created opening throughout thetrabecular meshwork. Once the created openings close, the pressurebuilds back up and the surgery fails.

Trabeculopuncture: Q-switched Neodymiun (Nd):YAG lasers also have beeninvestigated as an optically invasive technique for creatingfull-thickness holes in trabecular meshwork. However, the relativelysmall hole created by this trabeculopuncture technique exhibits afilling in effect and fails.

Goniophotoablation/Laser Trabecular Ablation: Goniophotoablation isdisclosed by Berlin in U.S. Pat. No. 4,846,172, and describes the use ofan excimer laser to treat glaucoma by ablating the trabecular meshwork.This was not demonstrated by clinical trial to succeed. Hill et al. usedan Erbium:YAG laser to create full thickness holes through trabecularmeshwork (Hill et al., Lasers in Surgery and Medicine 11:341-346, 1991).This technique was investigated in a primate model and a limited humanclinical trial at the University of California, Irvine. Althoughmorbidity was zero in both trials, success rates did not warrant furtherhuman trials. Failure again was from filling in of created defects intrabecular meshwork by repair mechanisms. Neither of these is a validsurgical technique for the treatment of glaucoma.

Goniocurretage: This is an ab-interno (from the inside) mechanicaldisruptive technique. This uses an instrument similar to a cyclodialysisspatula with a microcurrette at the tip. Initial results are similar totrabeculotomy that fails secondary to repair mechanisms and a process offilling in.

Although trabeculectomy is the most commonly performed filteringsurgery, Viscocanulostomy (VC) and non-penetrating trabeculectomy (NPT)are two new variations of filtering surgery. These are ab-externo (fromthe outside), major ocular procedures in which Schlemm's canal issurgically exposed by making a large and very deep scleral flap. In theVC procedure, Schlemm's canal is canulated and viscoelastic substanceinjected (which dilates Schlemm's canal and the aqueous collectorchannels). In the NPT procedure, the inner wall of Schlemm's canal isstripped off after surgically exposing the canal.

Trabeculectomy, VC, and NPT are performed under a conjunctival andscleral flap, such that the aqueous humor is drained onto the surface ofthe eye or into the tissues located within the lateral wall of the eye.Normal physiological outflows are not used. These surgical operationsare major procedures with significant ocular morbidity. WhenTrabeculectomy, VC, and NPT are thought to have a low chance forsuccess, a number of implantable drainage devices have been used toensure that the desired filtration and outflow of aqueous humor throughthe surgical opening will continue. The risk of placing a glaucomadrainage implant also includes hemorrhage, infection and postoperativedouble vision that is a complication unique to drainage implants.

Examples of implantable shunts or devices for maintaining an opening forthe release of aqueous humor from the anterior chamber of the eye to thesclera or space underneath conjunctiva have been disclosed in U.S. Pat.No. 6,007,511 (Prywes), U.S. Pat. No. 6,007,510 (Nigam), U.S. Pat. No.5,893,837 (Eagles et al.), U.S. Pat. No. 5,882,327 (Jacob), U.S. Pat.No. 5,879,319 (Pynson et al.), U.S. Pat. No. 5,807,302 (Wandel), U.S.Pat. No. 5,752,928 (de Roulhac et al.), U.S. Pat. No. 5,743,868 (Brownet al.), U.S. Pat. No. 5,704,907 (Nordquist et al.), U.S. Pat. No.5,626,559 (Solomon), 5,626,558 (Suson), U.S. Pat. No. 5,601,094 (Reiss),U.S. Pat. No. RE. 35,390 (Smith), U.S. Pat. No. 5,558,630 (Fisher), U.S.Pat. No. 5,558,629 (Baerveldt et al.), U.S. Pat. No. 5,520,631(Nordquist et al.), U.S. Pat. No. 5,476,445 (Baerveldt et al.), U.S.Pat. No. 5,454,796 (Krupin), U.S. Pat. No. 5,433,701 (Rubinstein), U.S.Pat. No. 5,397,300 (Baerveldt et al.), U.S. Pat. No. 5,372,577(Ungerleider), U.S. Pat. No. 5,370,607 (Memmen), U.S. Pat. No. 5,338,291(Speckman et al.), U.S. Pat. No. 5,300,020 (L'Esperance, Jr.), U.S. Pat.No. 5,178,604 (Baerveldt et al.), U.S. Pat. No. 5,171,213 (Price, Jr.),U.S. Pat. No. 5,041,081 (Odrich), U.S. Pat. No. 4,968,296 (Ritch etal.), U.S. Pat. No. 4,936,825 (Ungerleider), U.S. Pat. No. 4,886,488(White), U.S. Pat. No. 4,750,901 (Molteno), U.S. Pat. No. 4,634,418(Binder), U.S. Pat. No. 4,604,087 (Joseph), U.S. Pat. No. 4,554,918(White), U.S. Pat. No. 4,521,210 (Wong), U.S. Pat. No. 4,428,746(Mendez), U.S. Pat. No. 4,402,681 (Haas et al.), U.S. Pat. No. 4,175,563(Arenberg et al.), and U.S. Pat. No. 4,037,604 (Newkirk).

All of the above embodiments and variations thereof have numerousdisadvantages and moderate success rates. They involve substantialtrauma to the eye and require great surgical skill by creating a holeover the full thickness of the sclera/cornea into the subconjunctivalspace. Furthermore, normal physiological outflow pathways are not used.The procedures are mostly performed in an operating room generating afacility fee, anesthesiologist's professional fee and have a prolongedrecovery time for vision. The complications of filtration surgery haveinspired ophthalmic surgeons to look at other approaches to loweringintraocular pressure.

The trabecular meshwork and juxtacanilicular tissue together provide themajority of resistance to the outflow of aqueous and, as such, arelogical targets for surgical removal in the treatment of open-angleglaucoma. In addition, minimal amounts of tissue are altered andexisting physiologic outflow pathways are utilized. Trabecular bypasssurgery has the potential for much lower risks of choroidal hemorrhage,infection and uses existing physiologic outflow mechanisms. This surgerycould be performed under topical anesthesia in a physician's office withrapid visual recovery.

Therefore, there is a great clinical need for the treatment of glaucomaby a method that would be faster, safer and less expensive thancurrently available modalities. Trabecular bypass surgery is aninnovative surgery which uses a micro stent, shunt, or other implant tobypass diseased trabecular meshwork alone at the level of trabecularmeshwork and use or restore existing outflow pathways. The object of thepresent invention is to provide a means and methods for treatingelevated intraocular pressure in a manner which is simple, effective,disease site specific and can be performed on an outpatient basis.

SUMMARY OF THE INVENTION

In some preferred embodiments, the seton has an inlet portion configuredto extend through a portion of the trabecular meshwork of an eye, and anoutlet portion configured to extend into Schlemm's canal of the eye,wherein the inlet portion is disposed at an angle relative to the outletportion. In some embodiments, the outlet portion has a lumen with anoval cross-section having a long axis.

The outlet portion in certain embodiments has a longitudinal axis, suchthat the long axis of the oval cross-section and the longitudinal axisof the outlet portion define a plane, the inlet portion having alongitudinal axis which lies outside the plane at an angle θ (theta)thereto.

In some preferred arrangements, the seton comprises an inlet portion,configured to extend through a portion of the trabecular meshwork; anoutlet portion, configured to extend into Schlemm's canal; and at leastone protrusion on the outlet portion, configured to exert tractionagainst an inner surface of Schlemm's canal. This protrusion cancomprise at least one barb or ridge.

Some preferred embodiments comprise an inlet portion configured toextend through a portion of the trabecular meshwork, an outlet portionconfigured to extend into Schlemm's canal, and a one-way valve withinthe inlet and/or outlet portions.

A method for delivering a seton within an eye is disclosed, comprisingproviding an elongate guide member, advancing a distal end of the guidemember through at least a portion of the trabecular meshwork of the eye,advancing the seton along the guide member toward the distal end, andpositioning the seton to conduct aqueous humor between the anteriorchamber of the eye and Schlemm's canal.

In certain embodiments, the advancing of the guide member comprisesadvancing it from the anterior chamber into the trabecular meshwork. Infurther embodiments, the positioning comprises positioning an end of theseton within Schlemm's canal adjacent to an aqueous collection channel.

Certain preferred embodiments include an apparatus for delivering aseton to the anterior chamber of an eye comprising an elongate tubehaving a lumen, an outer surface, and a distal end; a removable,elongate guide member within the lumen, configured to permit the setonto be advanced and to be positioned in the trabecular meshwork of theeye. This apparatus can further comprise a cutting member positioned atthe distal end of the tube. The cutting member can be selected from thegroup consisting of a knife, a laser probe, a pointed guide member, asharpened distal end of said tube, and an ultrasonic cutter. Theapparatus can also further comprise an opening in the outer surface ofthe tube, configured to allow fluid infusion into the eye.

In further preferred embodiments, an apparatus for delivering a seton inan eye, comprises an elongate member adapted for insertion into ananterior chamber of the eye, the elongate member having a distal endportion configured to retain the seton therein, the distal end portioncomprising a cutting member configured to form an opening in thetrabecular meshwork of the eye for receipt of the seton, such that oneend of the seton is in Schlemm's canal. The elongate member can furthercomprise a lumen which conducts fluid toward said distal end portion.

The preferred embodiment provides further surgical treatment of glaucoma(trabecular bypass surgery) at the level of trabecular meshwork andrestores existing physiological outflow pathways. An implant bypassesdiseased trabecular meshwork at the level of trabecular meshwork andwhich restores existing physiological outflow pathways. The implant hasan inlet end, an outlet end and a lumen therebetween. The inlet ispositioned in the anterior chamber at the level of the internaltrabecular meshwork and the outlet end is positioned at about theexterior surface of the diseased trabecular meshwork and/or into fluidcollection channels of the existing outflow pathways.

In accordance with a preferred method, trabecular bypass surgery createsan opening or a hole through the diseased trabecular meshwork throughminor microsurgery. To prevent “filling in” of the hole, a biocompatibleelongated implant is placed within the hole as a seton, which mayinclude, for example, a solid rod or hollow tube. In one exemplaryembodiment, the seton implant may be positioned across the diseasedtrabecular meshwork alone and it does not extend into the eye wall orsclera. In another embodiment, the inlet end of the implant is exposedto the anterior chamber of the eye while the outlet end is positioned atthe exterior surface of the trabecular meshwork. In another exemplaryembodiment, the outlet end is positioned at and over the exteriorsurface of the trabecular meshwork and into the fluid collectionchannels of the existing outflow pathways. In still another embodiment,the outlet end is positioned in the Schlemm's canal. In an alternativeembodiment, the outlet end enters into fluid collection channels up tothe level of the aqueous veins with the seton inserted in a retrogradeor antegrade fashion.

According to the preferred embodiment, the seton implant is made ofbiocompatible material, which is either hollow to allow the flow ofaqueous humor or solid biocompatible material that imbibes aqueous. Thematerial for the seton may be selected from the group consisting ofporous material, semi-rigid material, soft material, hydrophilicmaterial, hydrophobic material, hydrogel, elastic material, and thelike.

In further accordance with the preferred embodiment, the seton implantmay be rigid or it may be made of relatively soft material and issomewhat curved at its distal section to fit into the existingphysiological outflow pathways, such as Schlemm's canal. The distalsection inside the outflow pathways may have an oval shape to stabilizethe seton in place without undue suturing. Stabilization or retention ofthe seton may be further strengthened by a taper end and/or by at leastone ridge or rib on the exterior surface of the distal section of theseton, or other surface alterations designed to retain the seton.

In one embodiment, the seton may include a micropump, one way valve, orsemi-permeable membrane if reflux of red blood cells or serum proteinbecomes a clinical problem. It may also be useful to use a biocompatiblematerial that hydrates and expands after implantation so that the setonis locked into position around the trabecular meshwork opening or aroundthe distal section of the seton.

One of the advantages of trabecular bypass surgery, as disclosed herein,and the use of a seton implant to bypass diseased trabecular meshwork atthe level of trabecular meshwork and thereby use existing outflowpathways is that the treatment of glaucoma is substantially simpler thanin existing therapies. A further advantage of the invention is theutilization of simple microsurgery that may be performed on anoutpatient basis with rapid visual recovery and greatly decreasedmorbidity. Finally, a distinctly different approach is used than isfound in existing implants. Physiological outflow mechanisms are used orre-established by the implant of the present invention, incontradistinction with previously disclosed methodologies.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and features of the present invention will becomemore apparent and the invention itself will be best understood from thefollowing Detailed Description of Exemplary Embodiments, when read withreference to the accompanying drawings.

FIG. 1 is a sectional view of an eye for illustration purposes.

FIG. 2 is a close-up sectional view, showing the anatomical diagram oftrabecular meshwork and the anterior chamber of the eye.

FIG. 3 is an embodiment of the seton implant constructed according tothe principles of the invention.

FIG. 4 is a top cross-sectional view of section 1—1 of FIG. 3.

FIG. 4A is a schematic view of the seton of FIG. 3 having plural lumems.

FIG. 5 is another embodiment of the seton implant constructed inaccordance with the principles of the invention.

FIG. 6 is a perspective view illustrating the seton implant of thepresent invention positioned within the tissue of an eye.

FIG. 7 is an alternate exemplary method for placing a seton implant atthe implant site.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 7, what is shown is a method for the treatmentof glaucoma by trabecular bypass surgery. In particular, a seton implantis used to bypass diseased trabecular meshwork at the level oftrabecular meshwork to use or restore existing outflow pathways andmethods thereof.

For background illustration purposes, FIG. 1 shows a sectional view ofan eye 10, while FIG. 2 shows a close-up view, showing the relativeanatomical locations of the trabecular meshwork, the anterior chamber,and Schlemm's canal. Thick collagenous tissue known as sclera 11 coversthe entire eye 10 except that portion covered by the cornea 12. Thecornea 12 is a thin transparent tissue that focuses and transmits lightinto the eye and the pupil 14 which is the circular hole in the centerof the iris 13 (colored portion of the eye). The cornea 12 merges intothe sclera 11 at a juncture referred to as the limbus 15. The ciliarybody 16 begins internally in the eye and extends along the interior ofthe sclera 11 and becomes the choroid 17. The choroid 17 is a vascularlayer of the eye underlying retina 18. The optic nerve 19 transmitsvisual information to the brain and is sequentially destroyed byglaucoma.

The anterior chamber 20 of the eye 10, which is bound anteriorly by thecornea 12 and posteriorly by the iris 13 and lens 26, is filled withaqueous. Aqueous is produced primarily by the ciliary body 16 andreaches the anterior chamber angle 25 formed between the iris 13 and thecornea 12 through the pupil 14. In a normal eye, the aqueous is removedthrough the trabecular meshwork 21. Aqueous passes through trabecularmeshwork 21 into Schlemm's canal 22 and through the aqueous veins 23which merge with blood-carrying veins and into venous circulation.Intraocular pressure of the eye 10 is maintained by the intricatebalance of secretion and outflow of the aqueous in the manner describedabove. Glaucoma is characterized by the excessive buildup of aqueousfluid in the anterior chamber 20 which produces an increase inintraocular pressure (fluids are relatively incompressible and pressureis directed equally to all areas of the eye).

As shown in FIG. 2, the trabecular meshwork 21 constitutes a smallportion of the sclera 11. It is understandable that creating a hole oropening for implanting a device through the tissues of the conjunctiva24 and sclera 11 is relatively a major surgery as compared to a surgeryfor implanting a device through the trabecular meshwork 21 only. A setonimplant 31 of the present invention for either using or restoringexisting outflow pathways positioned through the trabecular meshwork 21is illustrated in FIG. 5.

In a first embodiment, a method for increasing aqueous humor outflow inan eye of a patient to reduce the intraocular pressure therein. Themethod comprises bypassing diseased trabecular meshwork at the level ofthe trabecular meshwork and thereby restoring existing outflow pathways.Alternately, a method for increasing aqueous humor outflow in an eye ofa patient to reduce an intraocular pressure therein is disclosed. Themethod comprises bypassing diseased trabecular meshwork at a level ofsaid trabecular meshwork with a seton implant and using existing outflowpathways. The seton implant 31 may be an elongated seton or otherappropriate shape, size or configuration. In one embodiment of anelongated seton implant, the seton has an inlet end, an outlet end and alumen therebetween, wherein the inlet end is positioned at an anteriorchamber of the eye and the outlet end is positioned at about an exteriorsurface of said diseased trabecular meshwork. Furthermore, the outletend may be positioned into fluid collection channels of the existingoutflow pathways. Optionally, the existing outflow pathways may compriseSchlemm's canal 22. The outlet end may be further positioned into fluidcollection channels up to the level of the aqueous veins with the setoninserted either in a retrograde or antegrade fashion with respect to theexisting outflow pathways.

In a further alternate embodiment, a method is disclosed for increasingaqueous humor outflow in an eye of a patient to reduce an intraocularpressure therein. The method comprises (a) creating an opening intrabecular meshwork, wherein the trabecular meshwork comprises aninterior side and exterior side; (b) inserting a seton implant into theopening; and (c) transporting the aqueous humor by said seton implant tobypass the trabecular meshwork at the level of said trabecular meshworkfrom the interior side to the exterior side of the trabecular meshwork.

FIG. 3 shows an embodiment of the seton implant 31 constructed accordingto the principles of the invention. The seton implant may comprise abiocompatible material, such as a medical grade silicone, for example,the material sold under the trademark SILASTIC™, which is available fromDow Corning Corporation of Midland, Mich., or polyurethane, which issold under the trademark PELLETHANE™, which is also available from DowCorning Corporation. In an alternate embodiment, other biocompatiblematerials (biomaterials) may be used, such as polyvinyl alcohol,polyvinyl pyrolidone, collagen, heparinized collagen,tetrafluoroethylene, fluorinated polymer, fluorinated elastomer,flexible fused silica, polyolefin, polyester, polysilison, mixture ofbiocompatible materials, and the like. In a further alternateembodiment, a composite biocompatible material by surface coating theabove-mentioned biomaterial may be used, wherein the coating materialmay be selected from the group consisting of polytetrafluoroethlyene(PTFE), polyimide, hydrogel, heparin, therapeutic drugs, and the like.

The main purpose of the seton implant is to assist in facilitating theoutflow of aqueous in an outward direction 40 into the Schlemm's canaland subsequently into the aqueous collectors and the aqueous veins sothat the intraocular pressure is balanced. In one embodiment, the setonimplant 31 comprises an elongated tubular element having a distalsection 32 and an inlet section 44. A rigid or flexible distal section32 is positioned inside one of the existing outflow pathways. The distalsection may have either a tapered outlet end 33 or have at least oneridge 37 or other retention device protruding radially outwardly forstabilizing the seton implant inside said existing outflow pathwaysafter implantation. For stabilization purposes, the outer surface of thedistal section 32 may comprise a stubbed surface, a ribbed surface, asurface with pillars, a textured surface, or the like. The outer surface36, including the outer region 35 and inner region 34 at the outlet end33, of the seton implant is biocompatible and tissue compatible so thatthe interaction/irritation between the outer surface and the surroundingtissue is minimized. The seton implant may comprise at least one openingat a location proximal the distal section 32, away from the outlet end33, to allow flow of aqueous in more than one direction. The at leastone opening may be located on the distal section 32 at about opposite ofthe outlet end 33.

In another exemplary embodiment, the seton implant 31 may have a one-wayflow controlling means 39 for allowing one-way aqueous flow 40. Theone-way flow controlling means 39 may be selected from the groupconsisting of a check valve, a slit valve, a micropump, a semi-permeablemembrane, or the like. To enhance the outflow efficiency, at least oneoptional opening 41 in the proximal portion of the distal section 32, ata location away from the outlet end 33, and in an exemplary embodimentat the opposite end of the outlet end 33, is provided.

FIG. 4 shows a top cross-sectional view of FIG. 3. The shape of theopening of the outlet end 33 and the remaining body of the distalsection 32 may be oval, round or some other shape adapted to conform tothe shape of the existing outflow pathways. This configuration willmatch the contour of Schlemm's canal to stabilize the inlet section withrespect to the iris and cornea by preventing rotation.

As shown in FIG. 3, the seton implant of the present invention may havea length between about 0.5 mm to over a meter, depending on the bodycavity the seton implant applies to. The outside diameter of the setonimplant may range from about 30 μm to about 500 μm. The lumen diameteris preferably in the range between about 20 μm to about 150 μm. As shownin FIG. 4A, the seton implant may have a plurality of lumens 34 a tofacilitate multiple flow transportation. The distal section may becurved at an angle between about 30 degrees to about 150 degrees, in anexemplary embodiment at around 70-110 degrees, with reference to theinlet section 44.

FIG. 5 shows another embodiment of the seton implant 45 constructed inaccordance with the principles of the invention. In an exemplaryembodiment, the seton implant 45 may comprise at least two sections: aninlet section 47 and an outlet section 46. The outlet section has anoutlet opening 48 that is at the outlet end of the seton implant 45. Theshape of the outlet opening 48 is preferably an oval shape to conform tothe contour of the existing outflow pathways. A portion of the inletsection 47 adjacent the joint region to the outlet section 46 will bepositioned essentially through the diseased trabecular meshwork whilethe remainder of the inlet section 47 and the outlet section 46 areoutside the trabecular meshwork. As shown in FIG. 5, the long axis ofthe oval shape opening 48 lies in a first plane formed by an X-axis anda Y-axis. To better conform to the anatomical contour of the anteriorchamber 20, the trabecular meshwork 21 and the existing outflowpathways, the inlet section 47 may preferably lie at an elevated secondplane, at an angle θ, from the first plane formed by an imaginary inletsection 47A and the outlet section 46. The angle θ may be between about30 degrees and about 150 degrees.

FIG. 6 shows a perspective view illustrating the seton implant 31, 45 ofthe present invention positioned within the tissue of an eye 10. Ahole/opening is created through the diseased trabecular meshwork 21. Thedistal section 32 of the seton implant 31 is inserted into the hole,wherein the inlet end 38 is exposed to the anterior chamber 20 while theoutlet end 33 is positioned at about an exterior surface 43 of saiddiseased trabecular meshwork 21. In a further embodiment, the outlet end33 may further enter into fluid collection channels of the existingoutflow pathways.

In one embodiment, the means for forming a hole/opening in thetrabecular mesh 21 may comprise an incision with a microknife, anincision by a pointed guidewire, a sharpened applicator, a screw shapedapplicator, an irrigating applicator, or a barbed applicator.Alternatively, the trabecular meshwork may be dissected off with aninstrument similar to a retinal pick or microcurrette. The opening mayalternately be created by retrogade fiberoptic laser ablation.

FIG. 7 shows an illustrative method for placing a seton implant at theimplant site. An irrigating knife or applicator 51 comprises a syringeportion 54 and a cannula portion 55. The distal section of the cannulaportion 55 has at least one irrigating hole 53 and a distal space 56 forholding a seton implant 31. The proximal end 57 of the lumen of thedistal space 56 is sealed from the remaining lumen of the cannulaportion 55.

For positioning the seton 31 in the hole or opening through thetrabecular meshwork, the seton may be advanced over the guidewire or afiberoptic (retrograde). In another embodiment, the seton is directlyplaced on the delivery applicator and advanced to the implant site,wherein the delivery applicator holds the seton securely during thedelivery stage and releases it during the deployment stage.

In an exemplary embodiment of the trabecular meshwork surgery, thepatient is placed in the supine position, prepped, draped and anesthesiaobtained. In one embodiment, a small (less than 1 mm) self sealingincision is made. Through the cornea opposite the seton placement site,an incision is made in trabecular meshwork with an irrigating knife. Theseton 31 is then advanced through the cornea incision 52 across theanterior chamber 20 held in an irrigating applicator 51 undergonioscopic (lens) or endoscopic guidance. The applicator is withdrawnand the surgery concluded. The irrigating knife may be within a sizerange of 20 to 40 gauges, preferably about 30 gauge.

From the foregoing description, it should now be appreciated that anovel approach for the surgical treatment of glaucoma has been disclosedfor releasing excessive intraocular pressure. While the invention hasbeen described with reference to a specific embodiment, the descriptionis illustrative of the invention and is not to be construed as limitingthe invention. Various modifications and applications may occur to thosewho are skilled in the art, without departing from the true spirit andscope of the invention, as described by the appended claims.

1. A device for treating glaucoma, comprising: an ocular implant ofbiocompatible material sized and shaped to facilitate the transport ofaqueous humor from the anterior chamber of the eye to and withinSchlemm's canal, said implant comprising first and second lumens, eachof which bypasses the trabecular meshwork and terminates in Schlemm'scanal, so as to receive aqueous humor from the anterior chamber andtransport said aqueous humor into Schlemm's canal.